In the construction industry many structures are important to the overall structural integrity and soundness of a building or built structure. Typically the ceiling is a hard, sound-reflecting material such as wood, plaster or concrete. Noises and other sounds spread throughout the room with little or no noise reduction; and noise levels build up in unmodified ceilings. Attempts to minimize such build-up noise include the practice to make ceilings with sound absorbing material such as acoustical tiles that are typically flat squares of porous material dimensioned to fit within the openings of a standard suspended ceiling or wall panel. Such noise reducing tiles are particularly effective for trapping and absorbing medium wavelength sound between about 1 kilohertz and 2 kilohertz, a very narrow band of the audible sound spectrum but typically not a broader noise band.
While conventional planar ceiling systems work well in limiting medium wavelengths of the audible range, they leave much to be desired where there is substantial sound in the range between 4 kilohertz and 8 kilohertz and 100 hertz to 800 hertz or outside the range of 500 to 2000 hertz. Longer wavelength sounds encountered in many office and industrial settings are not easily trapped or absorbed. Portions of these non-absorbed sound waves easily penetrate the planar ceiling or wall in a coherent wave front. Thus, traditional noise reduction ceiling tiles and wall panels have very poor performance in noise reduction factors.
Anechoic type tiles have been designed in the past with relatively complex geometries for absorbing more of a spectrum of sound. These types of tiles, however, are not generally suitable for economical manufacture, installation or use in commercial applications. Further these types of tiles are not suitable for retrofit into existing acoustical ceiling or wall surfaces and would be undesirable in occupied buildings.
Ceiling tiles have been made from mineral fibers and cellulosic fibers using a slurry process which involves a high percentage of water in the process that must be evaporated to form the tile. Further, there is a significant amount of waste water from the process that must be cleaned up and may not be reused.
Traditional ceiling tiles have poor noise reduction factors and typically have noise reduction in the range of 500 to 2,000 hz.
Traditional ceiling tiles are heavy and dense to be able span grids of 2′×2′ or 2′×4′. Further, they are subject to water staining from leaky roofs or water drips. Further most ceiling tiles suffer from mold and mildew, as well as bacterial growth.
Traditional ceiling tiles are not readily recycled back into themselves. Generally, they cannot achieve 90% recycled content or greater.
In addition most common building materials such as wood, metal and masonry have hard surfaces and thus reflect sound. Further some materials have coatings such as latex to seal the material. Such materials are considered sound “reflective” barriers. When sound strikes the surface of a reflective barrier, some energy is transmitted through the ceiling tile or panel but the bulk is reflected back in the general direction of the noise source. Depending upon the roughness and shape of the surface, and the wavelength of the sound, the sound may be fractured in different directions. This is not desirable for several reasons including having sound reflected back to the source that may cause vibrations in the structure holding the ceiling tiles or panels. As with interior building materials, the use of sound absorptive is preferable.
Therefore there exists a need for an acoustical ceiling tile or panel that will provide improved noise reduction, be sound absorptive rather than sound reflective and be manufactured in a process that utilized very little water, are made from recycled raw materials, can be recycled back into new tiles, are stain resistant, are anti-microbial resistant, and are lighter weight.
Thus there still exists a need for an acoustic absorber that is thermo-formable or otherwise moldable, light weight, resistant to water penetration and other environmental factors, flame resistance, and has a high RAYLS number.